The present invention is directed to an improved plasma discharge device and method for removing material from a substrate.
In the manufacture of semiconductor devices, it is frequently necessary to remove a substance from a substrate. The present invention is broadly applicable to such processes, and for example, would include specific processes relating to residue removal, chemical downstream etching (CDE), and etching.
It is known to use plasma discharge devices to remove a substance from a substrate, and these may be of the "afterglow" type, where it is the afterglow of the plasma rather than the plasma itself which accomplishes removal. While the gas used in the plasma is frequently oxygen, as for ashing applications, it may be a different gas such as a fluorine containing gas for other applications, as when materials such as heavily metallized polymeric residues are to be removed.
In a plasma discharge device, a gas is flowed through a plasma tube which is located in a microwave cavity, and a plasma is excited in the gas by microwave energy. Then, the plasma, or the afterglow therefrom is used to remove the material from the substrate.
One drawback of many plasma discharge devices for material removal is that they are designed for use with only a single type of gas, e.g., oxygen, or fluorine containing gas, as the case may be. This results in added expense since, when a process using a different gas is to be performed, a new piece of equipment must be used.